Behavioral, psychopharmacological and gender effects of stress on parochial altruism

人类是社会性动物，他们与他人合作，考虑他人的福祉，并接受个人成本来帮助他人。然而，无私的行为并不总是为了增加他人的幸福。有时，个人接受伤害他人的代价，即使伤害他人并不会带来更高的自身回报。利他的群体内合作与群体外攻击，即所谓的狭隘利他主义，是普遍存在的，潜在的认知、神经和内分泌机制可能共同进化。在第一个资助阶段，我们已经获得了行为和心理药理学证据，表明压力调节社会折扣，即社会距离依赖的慷慨水平。我们已经表明，压力会选择性地增加对社会上亲密的人（家人、朋友和其他内部成员）的慷慨，但不会增加对社会上疏远的人（邻居、陌生人等）的慷慨。有趣的是，我们第一项研究的相关数据以及第二项研究的精神药理学证据表明，内分泌应激反应的去甲肾上腺素能成分可能会减少而不是增加对他人的慷慨，这表明行为应激反应不仅仅是慷慨。此外，跨学科有一个显著的共识，即压力也会增加攻击性倾向，例如战斗反应。因此，我们假设，与压力相关的对社会关系密切的人（群体内）慷慨程度的增加，与对群体外成员利他性攻击的增加同时发生。此外，尽管性别差异的证据还远不清楚，但据推测，压力后慷慨和/或攻击性的变化与性别有关。因此，在第二个资助阶段，我们申请资助，以调查压力对狭隘利他主义的行为，神经内分泌和性别影响。我们将利用自然的群内群外结构来研究现实的群间竞争：政党选民之间存在的竞争。我们将使用几个行为任务，使我们能够解决1)在没有压力的情况下，狭隘主义在男性和女性之间是否普遍不同；2)使用特里尔社会压力测试的群体版本引发的社会心理压力是否会放大群体内合作和群体外仇恨；3)这些压力对狭隘主义的影响是否取决于性别。最后，我们预测，通过精神药理学手段增强交感神经（去甲肾上腺素），但不一定是糖皮质激素（皮质醇）的活性，可以模拟压力对狭隘利他主义的影响。我们提出的研究将完善我们对压力的社会反应的理解，以及其中的性别差异，但它们可能被推广到促进和维持群体间冲突以及反社会行为的因素。

Humans are social animals who cooperate with others, consider their well-being and accept personal costs to help them. However, selfless behavior is not always directed at increasing the well-being of other people. Sometimes, individuals accept costs to inflict harm on others, even if harming others does not result in higher own-payoff. Altruistic ingroup cooperation together with outgroup aggression, so-called parochial altruism, is widespread and the underlying cognitive, neural and endocrine mechanisms possibly coevolved. In a first funding phase, we have obtained behavioral and psychopharmacological evidence that stress modulates social discounting, i.e., social-distance-dependent levels of generosity. We have shown that stress selectively increases generosity towards socially close others (family, friends and other ingroup members), but not socially remote others (neighbors, strangers etc.). Interestingly, correlational data from our first study as well as psychopharmacological evidence from a second study suggests that the noradrenergic component of the endocrine stress response may decrease, rather than increase, generosity towards others, suggesting that there is more to the behavioral stress response than mere generosity. Moreover, there is remarkable consensus across disciplines that stress can also increase aggressive tendencies, e.g., fighting responses. We therefore hypothesize that the stress-related increase in generosity towards socially close people (ingroup) goes along with an increase in altruistic aggression against outgroup members. Moreover, it has been hypothesized that changes in generosity and/or aggression after stress are gender-dependent, although evidence for gender differences is far from clear. In a second funding phase, we therefore apply for funding to investigate the behavioral, neuroendocrine and gender effects of stress on parochial altruism. We will exploit a natural ingroup-outgroup structure to study realistic intergroup rivalry: existing rivalries between political party voters. We will employ several behavioral tasks allowing us to address 1) whether parochialism is different between men and women in general, i.e., in the absence of stress, 2) whether psychosocial stress, elicited using the group version of the Trier Social Stress Test, amplifies ingroup cooperation together with outgroup hate, and 3) whether these stress-effects on parochialism are gender-dependent. Finally, we predict that enhancing sympathetic (noradrenaline), but not necessarily glucocorticoid activity (cortisol) by psychopharmacological means mimics the effects of stress on parochial altruism. Our proposed studies will refine our understanding of the social response to stress, and gender differences therein, but they may be generalized to yield important insights into the factors promoting and maintaining intergroup conflicts as well as antisocial behavior.